@article{https://doi.org/10.1002/chem.202003842, author = {Gama, Sofia and Hermenau, Ron and Frontauria, Mariachiara and Milea, Demetrio and Sammartano, Silvio and Hertweck, Christian and Plass, Winfried}, title = {Iron Coordination Properties of Gramibactin as Model for the New Class of Diazeniumdiolate Based Siderophores}, journal = {Chemistry – A European Journal}, volume = {n/a}, number = {n/a}, pages = {}, keywords = {chemical speciation, diazeniumdiolate, iron(III) coordination, sequestering ability, siderophores}, doi = {https://doi.org/10.1002/chem.202003842}, url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202003842}, eprint = {https://chemistry-europe.onlinelibrary.wiley.com/doi/pdf/10.1002/chem.202003842}, abstract = {Abstract Gramibactin (GBT) is an archetype for the new class of diazeniumdiolate siderophores, produced by Paraburkholderia graminis, a cereal-associated rhizosphere bacterium, for which a detailed solution thermodynamic study exploring the iron coordination properties is reported. The acid-base behavior of gramibactin as well as its complexing ability toward Fe3+ was studied over a wide range of pH values (2≤pH≤11). For the latter the ligand-competition method employing EDTA was used. Only two species are formed: [Fe(GBT)]− (pH 2 to 9) and [Fe(GBT)(OH)2]3− (pH≥9). The formation of [Fe(GBT)]− and its occurrence in real systems was confirmed by LC-HRESIMS analysis of the bacteria culture broth extract. The sequestering ability of gramibactin was also evaluated in terms of the parameters pFe and pL0.5. Gramibactin exhibits a higher sequestering ability toward Fe3+ than EDTA and of the same order of magnitude as hydroxamate-type microbial siderophores, but smaller than most of the catecholate-type siderophores and much higher than the most known phytosiderophores.} }